Earth drilling



Dec. 29, 1931. 1 s. G. NOTTAGE EARTH DRILLING Filed Dec. .31, 1924 INVENTOR $70/7/ey Grv'gqs Nofiaqe ATTORNEY Patented Dec. 29, 1931 warren ATES PATENT OFFICE STANLEY GBIGGS NOTTAGE, OI MURBAYSVILLE, EPENNSYLVANIA, ASSIGNOB TO WEST- VANIA.

EARTH DRILLING Application filed December 31, 1924. Serial No. 759,079.

My invention relates to systems of motor control, and it has particular relation to such systems as are employed in connection with earth-drilling and similar applications.

An object of my invention is to provide electrical means for varying the pressure on the drilling tool in accordance with the resistance met in the drilling operation. 7

Certain prior systems employ mechanical devices for controlling the drilling pressure in accordance with the load, whereas, in accordance with my invention, the equipment is greatly simplified by employing two alternating-current induction motors, preferably having their primary windings connected in series relation.

The first motor, which is directly "connected I to the line, performs the customary drilling operation, while the second motor is governed in accordance with the current traversing the first motor and operates to relieve the pressure on the drill-bit in accordance with the load conditions.

My invention will be best understood by reference to the accompanyingdrawings in which r Fig. 1 illustrates a derrick, of a familiar character, em 10 ed in connection with rotary earth i1 ing, to which my invention is applied.

Fig. 2 is a diagrammatic representation of the scheme of main-circuit connections embodying my invention.

Referring to Fig. 1, an induction motor 1, preferably of the wound-rotor type, is corinected through suitable gearing to operate a rotary table 2. A, drill stem 3 is rotated by means of the table and is suspended by means of a cable 4 that is wound on a hoisting drum 5, in accordance with a familiar practice. The hoisting drum is operated by means of an induction motor 6, preferabl of the high-resistance squirrel-cage type. he motor 6 operates on the principle of a ftorquemotor, whereby,'its torque is exerted in opposition to the weight of the suspended tool 3 and it functions as a feed motor, in conjunction with the gravity feeding of the tool itself. f The primary windings 7 ofthe motor 6 receive energy through current traversing the series-related primary winding 8 of the drilling motor 1, as shown in Fig. 2. In 'order to regulate the torque developed by the motor 6, an auxiliary three-phase rheostat 9 is connected in shunt relation to the primary windings 7.

A rotary drilling rig is illustrated in the application of Frederic W. Hild, filed Mar. 22, 1921, Serial No. 454,451, which application illustrates the details of the rotary drilling connections and the customary means of 2 in the customary manner. When normal load current flows in the of the drilling motor, also traverses the primary windings 7 of the feed motor 6. Bymeans of the rheostat 9, the normal torque of the motor 6 may be so adjusted as to balance the desired portion of the weight comprising the drilling tool 3, so that proper fpressure is brought to bear pp the drill-bit, or any given earth formaion.

During the drilling operation, if an increased drilling resistance is met with, by reason of variations in the earth formation, a corresponding increase in current traversing the drilling motor likewise affects the feed motor, which tends to raise the drill 3 in extreme cases, and at least to increase the tension on the cable 4 and relieve the pressure on the drill bit.

It will be apparent to those skilled in the art.that the torque of the drilling motor is about proportional to the load current, whereas the torque of the feed motor will be proportional to the square of the current. utllize this effect in accordance with m invention to establish a desirable electricalifierential relation between these two motors. That is to say, the output of the motors and the corresponding drill-pressure depends upon the primary windings 8 this value of current load resistance and, if the load current is maintained constant, the respective motor torques must assume a definite relation to one another.

Additional weight is, of course, added to the drill as the depth of the drilling hole increases, and variations of torque required in the feeding motor are obtained by adjusting the rheostat 9.

Other modifications of my invention may occur to one skilled in the art. I have illustrated my invention in simple form to set forth what I believe to be a new combination and a new application of alternatingcurrent motors for various drilling operations. I do not desire to be limited to earth drilling, since my invention may. be readily adapted for other similar applications.

I claim as my invention:

1. In an earth-drilling system, the combination with a drilling tool, and an alternating-current induction motor therefor having a primary winding, of a second induction motor having a primary winding in series rela-' tion with the primary winding of the firstnamed motor for controlling the effect of said first motor.

2. In an earth-drilling system, the combination with a drilling tool, an alternatingcurrent tool-driving motor having a rotor winding and a stator winding, an alternating-current tool-feeding motor having a rotor and a stator winding and means for connecting the stator windings of said motors in series. I

3. In an earth-drilling system, the combiplurality of windings, a second alternatingcurrent tool-driving motor provided with a plurality of windings, a second alternatingcurrent tool-feeding motor provided with a plurality of windings, a source of a1- ternating-cur'rent power and means for connecting certain of the windings of each of said motors in series-circuit relation directly to said source of ower.

4. In an earth-drilling system, the combination with a drilling tool, an alternating-cur rent tool-driving motor and an alternatingcurrent tool-feeding motor, a circuit for energizing said motors including a winding of said first named motor and a winding of said second named motor connected in series circuit relation and directly connected to the circuit for energizing said motors and a rheostat connected to said circuit between the windings of said motors.

In testimony whereof, I have hereunto subscribed my name this 24th day of November,

' STANLEY G. NOTTAGE.

amen 

